Interior residential and light commercial flooring systems commonly include plywood or oriented strand board (OSB) nailed to a wooden frame. OSB consists of pieces of wood glued together. However, costs of lumber and labor required for installing wooden floors and framing components have risen with time. Wooden floors and framing components are also susceptible to water damage, fire damage, insect damage and rotting. Additional problems specifically associated with wooden floor joists include stability and quality.
Typical floor construction methods include installing “header” members (rim joists) on the top of support walls that may be fabricated from, for example, concrete blocks, wood or metal studs. In wood frame construction, the header members typically comprise wood beams that are supported on edge on the wall. Other wood beam members, commonly referred to as joists, are used to span from wall to wall between the headers and are usually connected to the headers by nails. The joists are typically arranged parallel to each other with 8″, 16″ or 24″ between their respective centers, depending upon the load characteristics that the floor must accommodate. A sheathing material such as plywood or OSB is then fastened to the upper edges of the joists using nails, screws or other mechanical fasteners to form the floor surface. To prevent the joists from twisting or moving laterally, small pieces of wood, known as blocking pieces, are commonly nailed between adjacent joists to form, in many instances, X-shaped braces between the joists. Insulation is sometimes installed between the joists and sheathing, drywall, plasterboard, etc. is then applied to the bottom of the joists to form a ceiling for the space located under the floor joist system. When connecting the joists to their respective headers, the carpenter must first measure and mark the headers to establish the desired joist spacing. After the headers are installed, the joists must be properly nailed to the headers by a carpenter. If the carpenter has access to the opposite side of the header from which the joist is to be installed, the nails are hammered through the header into the end of the respective joist. If, however, the carpenter cannot access the opposite side of the header, nails must be inserted at an angle (commonly referred to as “toe-nailing”) through the joist and into the header. Care must be taken to avoid inadvertently splitting the joist and to ensure that the nails extend through the joist and into the header a sufficient distance. Such attachment process can be time consuming and may require the use of skilled labor which can also lead to increase construction costs. If toe-nailing is not structurally acceptable, another piece, called a joist hanger is added which also increases labor and material costs.
Framing in metal, both when building out commercial spaces as well as residential structures, is becoming more and more common. Probably the best known and most prevalent method of framing in metal involves the use of metal channeling, typically rolled from sheet steel and sometimes aluminum. These metal framing members or studs, often used to erect and reinforce commercial and residential structures, are channels having a substantially C-shaped cross section with a broad web (base) and narrow flanges (sides) of uniform height. To enhance the stud or framing member's strength and rigidity, the edges of the flanges of the C-channel component are bent over to form lips parallel to the plane of the C-channel base to form the C-shaped component.
The outside dimensions of the metal framing members and studs, and the weight or gauge of the member or stud, vary. Typically the members are fabricated to be approximately 4 inches wide by 2 inches deep, corresponding thereby to the width and depth of wood framing and stud members, in which case the lips may extend ¼ to ½ inch from the sides of the studs. Fourteen to 20 gauge metal may be used for light gauge, residential construction and commercial wall construction. Heavier metal gauges are used in some residential and commercial framing and particularly in multiple story commercial construction.
There has developed a variety of methods for connecting and securing metal frames and wall studs. At the most basic level, metal studs are inserted into and secured within metal tracks by drilling, screwing, or welding from the outside wall of the track into an adjoining metal stud. Similarly, commercially available devices for interconnecting metal framing members, as for example tie brackets, shear connectors and plate connectors, typically use screws and bolts applied from the outside of the track or stud member inwards.
Metal studs and framing members have been modified to include saw or punch slots, tabs and brackets intended to facilitate the interconnection of these studs and framing member to adjoining studs and framing members and/or to cross-bars and other non-framing members that serve to reinforce the studs and framing members. Known connectors, including bracket, plate and tie connectors, presently used to tie together and interconnect metal studs, are generally drilled and screwed on site.
U.S. Pat. No. 6,799,407 discloses, a system for interconnecting metal framing members, tracks and studs by way of a variety of connectors and tracks. The connectors are specially configured and designed to fit within and interlock with the framing members, tracks and studs. The connectors serve to secure one member, track or stud to another member, track or stud, by fasteners applied from within the connector outwards into the non-surface aspects of the member, track or stud. The tracks are specially configured to utilize the novel connectors of the present invention to interconnect with other tracks or studs using fasteners applied from both the inside out, and the outside in, in three dimensions, while still leaving the surface aspects of tracks and studs free of fastener heads or other protrusions. It employs traditional C-channel shaped framing members or studs, made of sheet steel or aluminum. According to the system, the C-channel members comprise many or all framing components for commercial and residential construction as, for example, wall studs, tracks, headers, hips, floor joists, ceiling joists, roof trusses, fascia, stud blocking, etc. The framing members or studs are tied together by a collection of more than twenty-eight structurally related metal connectors specially configured and grooved to interlock within the familiar C-channel framing member. These connectors are secured to the studs using fasteners, typically self-tapping screws, inserted from within the connectors, through the connectors, and outward into the adjoining member or stud. Its system for interconnecting metal framing members, tracks and studs that can employ a member or stud of uniform dimension and that results in a frame having a smooth, continuous outer surface, devoid of protruding fasteners heads. This includes a system of interconnecting metal framing members in which fasteners are applied from the inside of the members outward, allowing the members to be secured by workers working entirely from within the building. The metal framing members, tracks and studs are interconnected in at least two, and often three, dimensions for additional strength and durability. Its connectors for interconnecting metal framing members and studs interlock within the framing members, tracks and studs that can be screwed and secured safely on site, without significant risk that the connector will be grabbed and spun by a powered drill or bit.
U.S. Pat. No. 5,687,538 discloses a structural framing member with a C-shaped cross section comprising of a main planar surface and two planar side walls at right angles. The side walls present an inwardly turned lip formed substantially parallel to the base. The capacity of the metal framing joist sections is increased by embossing longitudinal stiffeners perpendicular to the top and bottom side walls, with a minimum depth of 0.01″ (0.025 cm), continuous along the face of the main planar surface for the full length of the section. By bridging these longitudinal stiffeners with, but not limiting to, diagonal embossed stiffeners, a series of adjoining geometric shapes between longitudinal chords has been created to increase the rigidity of the web via adjoining geometric stiffeners which will carry the load by axial deformation rather than pure shear deformation.
U.S. Pat. No. 6,418,964 to Daudet et al, incorporated herein by reference, discloses floor joists and floor header systems made of metal. The system may include a joist rim that has at least one attachment tab integrally formed therein to facilitate attachment of a joist to the joist rim. Reinforcing ribs are preferably provided adjacent the attachment tabs for providing desired structural integrity to the attachment tab connection. The system may also include a C-shaped joist that has a plurality of oval-shaped openings to enable components such as ducts, wires, piping, etc. to pass there through. The joists may also be provided with a plurality of mounting holes that are adapted to accommodate wire retainer members for supporting insulation between respective joists. The system may also include preformed blocking members that are sized to extend between adjacent joists and be attached thereto to provide lateral support to the joists.
It is known to place plywood or OSB on cold formed, light gauge steel C-joists or steel open web bar joists. However, plywood and OSB are combustible.
U.S. Pat. No. 6,620,487 to Tonyan et al., incorporated herein by reference in its entirety, discloses a reinforced, lightweight, dimensionally stable structural cement panel (SCP) capable of resisting shear loads when fastened to framing equal to or exceeding shear loads provided by plywood or oriented strand board panels. The panels employ a core of a continuous phase resulting from the curing of an aqueous mixture of calcium sulfate alpha hemihydrate, hydraulic cement, an active pozzolan and lime, the continuous phase being reinforced with alkali-resistant glass fibers and containing ceramic microspheres, or a blend of ceramic and polymer microspheres, or being formed from an aqueous mixture having a weight ratio of water-to-reactive powder of 0.6/1 to 0.7/1 or a combination thereof. At least one outer surface of the panels may include a cured continuous phase reinforced with glass fibers and containing sufficient polymer spheres to improve nailability or made with a water-to-reactive powders ratio to provide an effect similar to polymer spheres, or a combination thereof.
U.S. Pat. No. 6,241,815 to Bonen, incorporated herein by reference in its entirety, also discloses formulations useful for SCP panels.
U.S. patent application Ser. No. 10/666,294, incorporated herein by reference, discloses a multi-layer process for producing structural cementitious panels (SCP's or SCP panels), and SCP's produced by such a process. After one of an initial deposition of loosely distributed, chopped fibers or a layer of slurry upon a moving web, fibers are deposited upon the slurry layer. An embedment device mixes the recently deposited fibers into the slurry, after which additional layers of slurry, then chopped fibers are added, followed by more embedment. The process is repeated for each layer of the board, as desired.
For use in construction, SCP panels should meet building code standards for shear resistance, load capacity, water-induced expansion and resistance to combustion, as measured by recognized tests, such as ASTM E72, ASTM 661, and ASTM C 1185 or equivalent, as applied to structural plywood sheets. SCP panels are also tested under ASTM E-136 for non-combustibility—plywood does not meet this test.
The SCP panel should be capable of being cut with the circular saws used to cut wood.
The SCP panel should be dimensionally stable when exposed to water, i.e., it should expand as little as possible, preferably less than 0.1% as measured by ASTM C 1185.
The SCP panel should provide a bondable substrate for exterior finish systems.
The SCP panel should be non-combustible as determined by ASTM E136.
After curing for 28 days, the flexural strength of a 0.75 inch (19. mm) thick SCP panel having a dry density of 65 to 90 lb/ft3 (1041 kg/m3) after being soaked in water for 48 hours should be at least 1000 psi (7 MPa), e.g. at least 1300 psi (9 MPa) preferably at least 1650 psi (11.4 MPa), more preferably at least 1700 psi (11.7 MPa), as measured by ASTM C 947. The panel should retain at least 75% of its dry strength.
In heavier commercial construction it is also common to form a floor by a “level pan” technique including laying steel I-beams or steel joists, e.g., open web bar joists, horizontally and then supporting a pan on the I-beams or joists and filling the pan with cement. Typically the pan has a corrugated bottom surface. However, this is expensive and time consuming.
There is a need for an economical, easy to assemble, durable and non-combustible total framing and flooring system.